1. Field of the Invention
This invention relates to a magnetic head of a construction in which two halves of core are joined together with a gap spacer therebetween, and more particular to a magnetic head used for an information recording and reproducing apparatus such as VTR and DAT.
2. Prior Art
FIG. 14 illustrates a structure before cutting process of one conventional magnetic head of a construction in which two halves of a core are joined together with a gap spacer sandwiched therebetween to form a magnetic gap. The gap spacer is made of, for example, a non-magnetic and hard material such as Al.sub.2 O.sub.3 and SiO.sub.2. The two core halves 3 made of magnetic material are formed with a winding groove 5 and track grooves 4 on the joint surfaces thereof. These joint surfaces are then mirror-polished, and are then deposited with a layer of Al.sub.2 O.sub.3 or SiO.sub.2 of a required thickness thereon by means of deposition or sputtering to form a gap spacer 1 as shown in FIG. 15. Then, as shown in FIG. 16, molten glass 2 is charged into the grooves 4 to securely combine the core halves together, forming a core block 8. The glass 2 is also charged into a bonding glass filling groove defined by portions 7 when the two halves are put together. Then, the core block 8 is cut along lines XVII--XVII into individual magnetic heads.
Generally, Al.sub.2 O.sub.3 does not exhibit good wettability by the glass 2, therefore when Al.sub.2 O.sub.3 is to be used as the gap spacer 1, it is difficult to adequately charge the glass in the vicinity of the gap. SiO.sub.2 is often corroded by the glass as shown at reference numeral 9 in FIG. 17, causing a difficulty of providing a reliable gap across the track.